Wireless Local Area Network (LAN) systems that are stipulated in a standard IEEE 802.11 have been improved in throughput year after year, and have come into widespread use as one example of main wireless access (Non-Patent Document 1). Because the wireless LAN system can be used in an unlicensed band that is a frequency band that does not require a license, various types of wireless terminals have come into widespread use. Particularly, the spread of smartphones remarkably increases an opportunity to use the wireless LAN system.
Because access control that is based on a CSMA/CA scheme is performed on the wireless LAN system in a 2.4 GHz band and a 5 GHz band, a case where throughput cannot be determined in conditions such as a Signal to Noise Ratio (SNR) of a physical link occurs, such as when throughput greatly decreases due to interference caused by a communication link in the vicinity. The greater the number of nodes that performs the access control that uses the CSMA/CA scheme, the more serious a problem.
Particularly, a decrease in throughput is also due to a hidden terminal problem and an exposed terminal problem. These influences are determined by a communication situation of a wireless station in the vicinity or a condition in which wireless stations detect each other. On the other hand, an attempt is made to interpret throughput characteristics in the CSMA/CA using a contention graph in which wireless stations that possibly detect each other, which can be defined with a graph theory are linked using edges and in which a communication link that is made from wireless stations or wireless stations for transmission and reception is taken as a vertex. However, there remain serious problems with estimation for an actual system, such as when a traffic condition of a wireless station in the vicinity is always assumed to be in a saturated state, when conditions in which the wireless station is detectable with transmission and reception are the same, or when only one of the uplink and the downlink is assumed.    Non-Patent Document 1: IEEE Std 802.11ac(TM)-2013, “IEEE Standard for Information technology—Telecommunications and information exchange between systems Local and metropolitan area networks—Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”, December 2013